The present invention relates to an electromagnetic valve for gaseous fluids. This type of valve has a special application as injector valve for gaseous fuels for internal combustion engines. The invention therefore also relates to an internal combustion engine provided with one or several such valves.
The problems caused by atmospheric pollution by means of exhaust gases from internal combustion engines such as car motors incite scientists and car manufacturers to look for new fuels and alternate fuels like for instance compressed natural gas or liquefied petroleum gas (LPG) which potentially offer an important reduction of the emission of polluting gases and greenhouse gases.
The present solutions for injection and metering of these new fuels for an internal combustion engine offer however not yet performances equal to the solutions used for normal petrol.
The principle for the known fuel systems for metering and mixing a gaseous fuel with inlet air to an internal combustion engine are based on the Venturi effect or on continuous injection of fuel. These systems have, however, typically an important number of mechanical components and do not offer the response times adequate to satisfy the sometimes important variations in the demand for fuel by the engine.
Thus, when these known injection systems for gaseous fuel are working together with for instance an associated exhaust gas purification system of the three-way catalytic converter type with lambda-probe control, their characteristics do not allow for the maintenance of the air to fuel ratio at the desired value during fast transitions in the engine load and speed in order to give an optimal purification of the exhaust gases.
One object of the present invention is to provide an electromagnetic valve for general gaseous fluids which can be used in many industrial applications in which there is a need for a simple wear resistant valve with an extremely short response time.
Another object of the invention is to provide an electromagnetic injector valve for gaseous fuels to e.g. an internal combustion engine. Such an injector valve could be mounted on the inlet or inlet manifold of an internal combustion engine for injecting the fuel. Due to the short response time of the valve it could be operated in pulsating mode.
The total response time for a traditional injection system for gaseous fuel is due to the operation of the actuator or actuators which are used for metering the fuel, the time for the transport of the gas mixture through the inlet tube or manifold to the respective cylinder and the characteristics for the transport of the fuel through the feeding tubes to the manifold.
The above and further objects are achieved by means of the present invention which is characterised in that the valve comprises:
an electromagnetic circuit which when activated generates an electromagnetic force for mechanical opening or closing of the valve,
a movable disk formed member at least part of which is included in said electromagnetic circuit and which disk formed member is guided in a linear movement perpendicular to the surface of said disk formed member,
a valve seat co-operating with the disk formed member providing the mechanical closing and sealing of the valve,
a resilient means which acts on the disk formed member,
a hole arranged downstream said valve seat the diameter of which hole preferably defines a sonic section for the gas flow which makes it possible to precisely adjust the quantity of gas let through as a function of the time during which the valve is in its open position irrespective of the downstream pressure.
Important advantages with a valve according to the invention is that it only has one (two if you count the spring) moving part(s), low inertia, extremely short response time and that it is very wear resistant.
When this type of valve is used as an injector valve for gaseous fuel for an internal combustion engine it makes possible the use of a pulsating mode for the injection of gas into the air flow introduced through the inlet or inlet manifold into the internal combustion engine allowing an optimal mixing of the two flows.
Due to the very simple but original design the reliability and life time are excellent.